arXiv subjects

Ya-Fang Guo

Publications and source records attributed to Ya-Fang Guo.

2 recordsLinked to original sources

arXiv2017

The Unit Cell Reconstruction and Related Thermal Activation Process within Coherent Twin Boundary Migration in Magnesium

By analyzing the interface defect loop nucleation and the interface disconnection expansion in dynamic simulations, the elementary migration process of coherent twin boundary of magnesium is identified to be independent unit cell reconstruction. The atomistic pathways of the unit cell reconstruction prove their collective behavior as a stochastic response to thermal fluctuation at a stressed state, and also the onset mechanism of interface disconnection gliding: predominant pure-shuffle basal-prismatic transformation along with atomistic shear movements. The athermal shear strength, the migration barrier, the critical length of disconnection dipole and other parameters characterizing the thermal activation process are reported.

cond-mat.mes-hall↗

arXiv2013

Size effect on deformation twinning at the nanoscale in hcp metals

Deformation twinning is generally considered to be the primary mechanism for hexagonal close-packed (hcp) metals due to their limited slip systems. Recent microcompression experiments on hcp metals point to intriguing strong size effects on twinning mechanisms, indicating that pyramidal slips dominate compression.In this work we analyze size effects on twinning due to lattice-rotation strain in hcp single crystals. A criterion for deformation twinning is derived at the nanoscale and tested by molecular dynamics simulations of magnesium and titanium single crystals. The results show pyramidal slip dominates the compression deformation at the nanoscale, consistent with experimental observations as well as our analysis. Our finding clarifies the nature of size effects in deformation twinning, while also providing an explanation for the so-called strength differential (SD) effect.

cond-mat.mtrl-sci↗